U.S. patent number 5,669,844 [Application Number 08/547,610] was granted by the patent office on 1997-09-23 for lubrication system for a parallel-axis differential.
This patent grant is currently assigned to Toyota Jidosha Kabushiki Kaisha, Zexel Corporation. Invention is credited to Akinori Homan, Kiyonari Ishikawa, Hirofumi Okuda.
United States Patent |
5,669,844 |
Homan , et al. |
September 23, 1997 |
**Please see images for:
( Certificate of Correction ) ** |
Lubrication system for a parallel-axis differential
Abstract
In a parallel-axis differential, a pair of sun gears are
received in a housing in a coaxial relation. Also, at least a pair
of planetary gears are received in the housing in parallel relation
with the sun gears. The planetary gears of the pair are in
engagement with the pair of sun gears, respectively and also in
engagement with each other. A window opening for introducing
lubricating oil is formed in the housing. Also, a fin for guiding
the lubricating oil toward the window opening is formed on the
outer surface of the housing. The fin is situated on the rear side
of the window opening with reference to one rotating direction of
said housing.
Inventors: |
Homan; Akinori (Toyota,
JP), Ishikawa; Kiyonari (Toyota, JP),
Okuda; Hirofumi (Saitama-ken, JP) |
Assignee: |
Toyota Jidosha Kabushiki Kaisha
(Aichi-ken, JP)
Zexel Corporation (Tokyo, JP)
|
Family
ID: |
17963621 |
Appl.
No.: |
08/547,610 |
Filed: |
October 24, 1995 |
Foreign Application Priority Data
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Nov 16, 1994 [JP] |
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6-306984 |
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Current U.S.
Class: |
475/160;
184/6.12; 475/252 |
Current CPC
Class: |
F16H
48/285 (20130101); F16H 57/0427 (20130101); F16H
57/0483 (20130101) |
Current International
Class: |
F16H
57/04 (20060101); F16H 057/04 () |
Field of
Search: |
;475/159,160,248,252
;184/6.12,11.1,13.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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22 19 258 |
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Nov 1972 |
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DE |
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29 45 226 C2 |
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May 1980 |
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DE |
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63-38586 |
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Aug 1988 |
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JP |
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4-19943 |
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Feb 1992 |
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JP |
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5-280596 |
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Oct 1993 |
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JP |
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6-18083 |
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May 1994 |
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JP |
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1620339 |
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Jan 1991 |
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SU |
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Primary Examiner: Marmor; Charles A.
Assistant Examiner: Jensen; Nathan O.
Claims
What is claimed is:
1. A parallel-axis differential, comprising:
(a) a housing rotatable about a rotational axis upon receipt of a
rotational torque, said housing having in a peripheral wall thereof
a window opening for allowing the passage of lubricating oil;
(b) a pair of sun gears rotatably received in said housing and
coaxial with said housing, said pair of sun gears being connected
with end portions of a pair of coaxial output shafts,
respectively;
(c) at least a pair of planetary gears rotatably received in said
housing and being parallel with the rotational axis of said
housing, said planetary gears of the pair being in engagement with
said pair of sun gears, respectively and also in engagement with
each other; and
(d) a fin mounted on an outer surface of the peripheral wall of
said housing, said fin including a primary portion and a secondary
portion, said primary portion of said fin being disposed along a
rear edge of said window opening with reference to one rotating
direction of said housing, said secondary portion of said fin
extending from said primary portion and away from said window
opening toward an end of said housing in a direction of said
rotational axis.
2. A parallel-axis differential according to claim 1, wherein said
primary portion of said fin is inclined such that it projects in
said rotating direction as it goes toward opposite ends of said
housing in the direction of said rotational axis.
3. A parallel-axis differential according to claim 1, wherein said
secondary portion of said fin is inclined such that it projects in
said rotating direction as it goes toward the end of said housing
in the direction of said rotational axis.
4. A parallel-axis differential according to claim 1, wherein the
primary portion and the secondary portion have a primary surface
and a secondary surface for guiding the lubricating oil,
respectively, said primary surface and the secondary surface being
inclined such that they project in the rotating direction as they
go radially outwardly.
5. A parallel-axis differential, comprising:
(a) a housing rotatable about a rotational axis upon receipt of a
rotational torque, said housing having end walls on opposite ends
in a direction of the rotational axis of said housing, and at least
one of said end walls is formed with a window opening for allowing
the passage of lubricating oil;
(b) a pair of sun gears rotatably receiving said housing and
coaxial with said housing, said pair of sun gears being connected
with end portions of a pair of coaxial output shafts,
respectively;
(c) at least a pair of planetary gears rotatably received in said
housing and being parallel with the rotational axis of said
housing, said planetary gears of the pair being in engagement with
said pair of sun gears, respectively and also in engagement with
each other; and
(d) a fin mounted on an outer surface of said at least one of said
end walls of said housing, said fin including a primary portion and
a secondary portion, said primary portion of said fin being
disposed along a rear edge of said window opening with reference to
said rotating direction of said housing, said secondary portion of
said fin extending radially outwardly from said primary portion of
said fin and away from said window opening.
6. A parallel-axis differential according to claim 5, wherein said
primary portion of said fin is inclined such that it projects in
said rotating direction as it goes radially outwardly of said
housing.
7. A parallel-axis differential according to claim 5, wherein said
secondary portion of said fin is inclined such that it projects in
said rotating direction as it goes radially outwardly of said
housing.
8. A parallel axis differential, comprising:
(a) a housing rotatable about a rotational axis upon receipt of a
rotational torque, said housing having a window opening for
allowing the passage of lubricating oil;
(b) a pair of sun gears rotatably received in said housing and
coaxial with said housing, said pair of sun gears being connected
with end portions of a pair of coaxial output shafts,
respectively;
(c) at least a pair of planetary gears rotatably received in said
housing and being parallel with the rotational axis of said
housing, said planetary gears of the pair being in engagement with
said pair of sun gears, respectively also in engagement with each
other; and
(d) a fin mounted on an outer surface of said housing; and said fin
being disposed on the rear side of said window opening with
reference to one rotating direction of said housing.
(e) a plate member separately situated from said housing, said
plate member including a fitting portion to be fitted in said
window opening, and said fin formed on an external edge of said
fitting portion.
Description
BACKGROUND OF THE INVENTION
This invention relates to a parallel-axis differential having sun
gears and planetary gear which are mutually in parallel
relation.
As disclosed in Japanese Laid-Open Patent Application No. Hei
5-280596, the parallel-axis differential for vehicles includes a
housing received in a differential carrier and rotationally driven
by an engine, a pair of sun gears rotatably received in and coaxial
with the housing, and plural pairs of planetary gears rotatably
supported within the housing and being in parallel relation with
the sun gears. The planetary gears of each pair are in engagement
with the pair of sun gears, respectively, and also in engagement
with each other. The pair of sun gears are connected with end
portions of a pair of coaxial output shafts, respectively.
In the above differential, when in differential rotation, one sun
gear having a larger load is rotated at a lower speed than the
housing and the other sun gear having a smaller load is rotated at
a higher speed than the housing. It is designed such that driving
torque transmitted to the housing is distributed to the pair of sun
gears at a ratio called "torque bias ratio" due to friction
generated between one end faces of the pair of sun gears, between
the other end faces of the pair of sun gears and an inner surface
of the housing, between one end face of each planetary gear and the
inner surface of the housing, and between an outer peripheral
surface of each planetary gear and the inner surface of the
housing.
In the differential disclosed by the Japanese Laid-Open Patent
Application No. Hei 5-280596, window openings are formed in a
peripheral wall and end walls of the housing. In accordance with
rotation of the housing, lubricating oil stored on a bottom portion
of the differential carrier is brought into the housing through the
window openings in order to lubricate and cool the mating surfaces
where the friction is generated, engaging portions between the
gears, etc.
In the above parallel-axis differential, the outer peripheral
surface of each planetary gear is in contact with the inner surface
of the housing. Owing to the necessity for obtaining this contact
area, it is practically impossible to form large window openings in
the peripheral wall of the housing. Therefore, it is demanded to
fulfill the requirement to supply a sufficient amount of
lubricating oil into the housing through even small window
openings.
In Japanese Laid-Open Utility Model Application No. Hei 4-19943 and
Japanese Utility Model Publication No. Hei 6-18083, there is
disclosed a differential of the type in which axes of planetary
gears are skewed with a co-axis of sun gears. In this differential,
a housing has fins projecting radially outwardly from a peripheral
wall thereof, so that lubricating oil stored in a differential
carrier can be guided toward window openings. FIG. 2 of the above
Japanese Utility Model Publication No. Hei 6-18083, especially,
shows a fin formed on an edge portion of the window opening which
edge portion is situated on a rear side in a rotating direction of
the housing.
Also, in Japanese Patent Publication No. Sho 63-38586, there is
disclosed a differential of the type in which axes of planetary
gears and a co-axis of sun gears are intersected at right angles.
FIG. 5 of this publication, especially, shows a lubricating oil
guiding fin formed on an edge portion of a window opening which
edge portion is situated on a rear side in a rotating direction of
a housing.
However, with respect to the parallel-axis differential, no
differential having a fin of the type as mentioned has been
developed.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a
parallel-axis differential capable of supplying a plenty of
lubricating oil into a housing through window openings.
According to the present invention, there is provided a
parallel-axis differential, comprising:
(a) a housing rotatable about a rotational axis upon receipt of a
rotational torque, the housing having a window opening for allowing
the passage of lubricating oil;
(b) a pair of sun gears rotatably received in the housing and
coaxial with the housing, the pair of sun gears being connected
with end portions of a pair of coaxial output shafts,
respectively;
(c) at least a pair of planetary gears rotatably received in the
housing and being parallel with the rotational axis of the housing,
the planetary gears of the pair being in engagement with the pair
of sun gears, respectively and also in engagement with each other;
and
(d) a fin mounted on an outer surface of the housing, the fin being
disposed on the rear side of the window opening with reference to
one rotating direction of the housing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a vertical sectional view of a differential according to
a first embodiment of the present invention;
FIG. 2 is a sectional view taken on line II--II of FIG. 1;
FIG. 3 is a front view of the differential when viewed in a
direction as indicated by an arrow III of FIG. 1;
FIG. 4 is a rear view of the differential when viewed in a
direction as indicated by an arrow IV of FIG. 1;
FIG. 5 is a perspective view showing a general construction of
gears in the differential. In this illustration, a housing is not
shown and only one pair of planetary gears are shown;
FIG. 6 is an enlarged view of a first window opening and a first
fin when viewed in a direction as indicated by an arrow VI of FIG.
1;
FIG. 7 is an enlarged view of a second window opening and a second
fin when viewed in a direction as indicated by an arrow VII of FIG.
1;
FIG. 8 is a view corresponding to FIG. 6 but showing modifications
of the first window opening and the first fin, respectively;
FIG. 9 is a view corresponding to FIG. 7 but showing modifications
of the second window opening and the second fin;
FIG. 10 is a sectional view showing further modifications of the
first window opening and the first fin;
FIG. 11 is a sectional view showing further modifications of the
second window opening and the second fin;
FIG. 12 is a vertical sectional view of a differential according to
a second embodiment of the present invention;
FIG. 13 is a front view of the differential when viewed in a
direction as indicated by an arrow XIII of FIG. 12;
FIG. 14 is a front view, partly in section, of a differential
according to a third embodiment of the present invention; and
FIG. 15 is a perspective view of a fin member to be used in the
third embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENT
A first embodiment of the present invention will now be described
with reference to FIGS. 1 to 7. As shown in FIGS. 1 and 2, a
parallel-axis differential for vehicles includes a housing 10 which
is received in a differential carrier, not shown. This housing 10
includes a sleeve portion 11, an end wall 12 integral with one end
of the sleeve portion 11, and a closure 13 (the other end wall) for
closing an opening in the other end of the sleeve portion 11. The
end wall 12 and closure 13 of the housing 10 are formed with
journal portions 12a and 13a, respectively. The housing 10 is
rotatably supported about an axis L through the journal portions
12a and 13a carried on bearings of the differential carrier. A ring
gear (not shown) is secured to the closure 13 of the housing 10.
The housing 10 receives a driving torque from an engine through the
ring gear and a gear which is in engagement with the ring gear.
A pair of cylindrical sun gears 20 are rotatably received in and
coaxial with the housing 10. The sun gears 20 have helical teeth 21
on their outer peripheries, respectively. The helical teeth 21 of
the pair of sun gears 20 are equal to each other in helical angle.
The helical direction of the helical teeth 21 of the pair of sun
gears 20 may be arranged either in a reverse direction or in the
same direction.
A pair of left and right axles 30 (output shafts, see FIG. 5) of
the vehicle extend through the journal portions 12a and 13a, with
end portions thereof being in spline-connection with spline
portions 22 of the pair of sun gears 20, respectively.
As shown in FIG. 2, three pairs of pockets 15 extending in parallel
relation to the axis L of the housing 1 are formed
circumferentially spacedly on an inner peripheral surface of the
sleeve portion 11 of the housing 10. The pockets 15 of each pair
are adjacent to each other. An inner peripheral surface of each
pocket 15 is cylindrical. Planetary gears 40 are rotatably received
in the pockets 15, respectively. The planetary gears 40 are in
parallel relation to the axis L of the housing 10. Each planetary
gear 40 is provided on opposite ends thereof with a first helical
teeth 41 long in an axial direction and a second helical teeth 42
short in the axial direction.
As most clearly shown in FIG. 5, the first helical teeth 41 of one
of the pair of planetary gears 40 is in engagement with one of the
pair of sun gears 20 and also in engagement with the second helical
teeth 42 of the other planetary gear 40. Similarly, the first
helical teeth 41 of the other planetary gear 40 is in engagement
with the other sun gear 20 and also in engagement with the second
helical teeth 42 of the first-mentioned planetary gear 40.
As shown in FIG. 1, a thrust washer 50A is interposed between the
pair of sun gears 20. Similarly, thrust washers 50B are interposed
respectively between the end wall 12 of the housing 10 and one of
the sun gears 20 and between the closure 13 and the other sun gear
20.
When in differential rotation, the planetary gears 40 are rotated
with outer peripheral surfaces (namely, top faces of the helical
teeth 41, 42) thereof being in contact with the inner peripheral
surfaces of the pockets 15, respectively, and friction is generated
therebetween. Friction is also generated between the pair of sun
gears 20 and the thrust washer 50A. Furthermore, friction is
generated between one of the sun gears 20 and the end wall 12, and
between the other sun gear 20 and the closure 13, through the
thrust washers 50B. A torque bias ratio is determined depending on
a sum of the afore-mentioned friction.
The above-mentioned construction is basically the same as the
conventional parallel-axis differential for vehicles. Next, a
construction for supplying lubricating oil into the housing 10 will
be described.
As most clearly shown in FIG. 2, three first window openings 60 and
three second window openings 70 for introducing lubricating oil
into the housing 10 are formed circumferentially alternately and at
equal intervals in the peripheral wall of the sleeve portion 11.
Each first window opening 60 is circular in configuration (see FIG.
6) and faced with an engaging portion between the pair of planetary
gears 40. Each second window opening 70 is oblong in configuration
in a direction of the axis n (see FIG. 7) and disposed between two
adjacent pairs of the planetary gears 40.
Fins 65, 75 for guiding lubricating oil toward the window openings
60, 70 are formed in the sleeve portion 11 in such a manner as to
project radially outwardly of the housing 10. As most clearly shown
in FIGS. 6 and 7, the fins 65, 75 include primary portions 65a, 75a
disposed respectively along rear edge portions (edge portions
situated on a rear side in a rotating direction R of the housing 10
when the vehicle travels forwardly) of the first window opening 60
and the second window opening 70, and a pair of secondary portions
65b, 75b extending in the direction of the rotational axis L toward
opposite ends of the housing 10.
Those surfaces 66, 76 of the fins 65, 75 facing the rotating
direction R are provided as guide surfaces, respectively. The guide
surfaces 66, 76 include primary surface portions 66a, 76a formed on
the primary portions 65a, 75a and secondary surface portions 66b,
76b formed on the secondary portions 65b, 75b, respectively.
The primary surface portion 66a of the guide surface 66 of the
first fin 65 is disposed along the edge portion of the rear side of
the circular window opening 60. The portion 66a is in a form of a
semi-cylindrical surface and continuous with a rear side portion of
an inner peripheral surface of the window opening 60. As a
consequence, the primary surface portion 66a is inclined such that
the portion 66a project forwardly in the rotating direction R as it
goes toward opposite ends of the housing 10 from the center along
the axis L. It should be noted that this primary surface portion
66a and the inner peripheral portion of the first window opening 60
corresponding thereto may be flat and inclined. The pair of
secondary surface portions 66b of the guide surface 66 of the first
fin 65 are of flat surfaces and intersected at right angles with
the rotating direction R. The primary surface portion 76a is
continuous with a rear side portion of an inner peripheral surface
of the second window opening 70. A central portion of the primary
surface portion 76a of the guide surface 76 of the second fin 75 is
of a flat surface intersecting at right angles with the rotating
direction R. Opposite end portions of the primary surface portion
76a are part of a cylindrical surface. As a consequence, opposite
end portions of the primary surface portion 76a are inclined such
that the opposite end portions project forwardly in the rotating
direction R as they go toward the opposite ends of the housing 10
along the axis L. It should be noted that the opposite end portions
of the primary surface portion 76a and the inner peripheral surface
portion of the second window opening 70 corresponding thereto may
be flat and inclined. The pair of secondary surface portions 76b of
the guide surface 76 of the second fin 75 are flat surfaces and
intersected at right angles with the rotating direction R.
As shown in FIG. 3, three semi-circular third window openings 80
are formed in intersecting portions between the end wall 12 of the
housing 10 and the sleeve portion 11. Each third window opening 80
is faced with an engaging portion of end portions of the planetary
gears 40 of each pair.
As shown in FIG. 4, six fourth window openings 90 are formed in the
closure 13 of the housing 10. Three of the fourth window openings
90 are arranged such that they correspond to the three pairs of
planetary gears 40, respectively, and the remaining three window
openings 90 are disposed between adjacent pairs of planetary gears
40, respectively.
In the parallel-axis differential thus constructed, when the
housing 10 is rotated in the rotating direction R while the vehicle
is traveling forwardly, lubrication oil stored on a bottom portion
of the differential carrier is brought into the housing 10 through
the window openings 60, 70, 80 and 90. The lubricating oil
introduced into the housing 10 is served to lubricate and cool the
mating surfaces where friction is generated and the engaging
portions between the gears.
Since the fins 65, 75 spoon and guide the lubricating oil toward
the window openings 60, 70 respectively, much more lubricating oil
can be supplied into the housing 10 through the window openings 60,
70. Accordingly, even in the presence of limitation of the opening
areas of the window openings 60 70, lubrication and cooling are
assuredly performed.
Since the primary surface portions 66a, 76a of the guide surfaces
66, 76 are inclined such that they prospect forwardly in the
rotating direction as they go toward the opposite ends of the
housing 10 along the axis L, much more lubricating oil can be
guided toward the window openings 60, 70.
Since the lubricating oil can also be spooned and partly sent into
the window openings 60, 70 by the secondary surface portions 66b,
76b, much more lubricating oil can be guided toward the window
openings 60, 70.
FIGS. 8 and 9 show modified embodiments of the first and second
fins 65, 75 formed on the peripheral wall of the housing 10.
Secondary portions 65b, 75b of those fins 65, 75 are inclined such
that they project forwardly in the rotating direction R as they go
toward opposite ends of a housing along a rotational axis of the
housing. As a consequence, secondary surface portions 66b, 76b of
guide surfaces 66, 76 are also inclined in the same manner.
According to this arrangement, lubricating oil spooned by the
secondary surface portions 66b, 76b can be sent respectively into
the window openings 60, 70 at a greater ratio.
FIGS. 10 and 11 show further modified embodiments of the first and
second fins 65, 75 formed on a peripheral wall of a housing. Guide
surfaces 66, 76 of those fins 65, 75 are inclined such that they
project forwardly in the rotating direction R as they go radially
outwardly of the housing. As a consequence, lubricating oil spooned
by the guide surfaces 66, 76 can be sent respectively into the
window openings 60, 70 at a greater ratio.
Further embodiments of the present invention will now be described.
In those embodiments, component parts corresponding to those of the
first embodiment are denoted by identical reference numerals and
detailed description thereof is omitted.
FIGS. 12 and 13 show a parallel-axis differential for vehicles
according to a second embodiment of the present invention. Three
circular window openings 100 are circumferentially equally spacedly
formed in an end wall 12. Each window opening 100 is disposed
between adjacent pairs of planetary gears 40. Also, three circular
window openings 110 are likewise formed in a closure 13.
Furthermore, a plurality of window openings 120 are
circumferentially equally spacedly formed in a sleeve portion
11.
Three fins 105 are formed on the end wall 12 in such a manner as to
correspond to the window openings 100 and project outwardly in a
direction of a rotational axis L. As most clearly shown especially
in FIG. 13, each fin 105 includes a primary portion 105a disposed
along a rear edge portion (an edge portion situated on the rear
side in a rotating direction R of the housing 10 when the vehicle
travels forwardly) of the corresponding window opening 100, and a
secondary portion 105b extending radially outwardly of the housing
10 from a radially external end of the primary portion 105a.
A surface 106 of each fin 105 facing in the rotating direction R is
provided as a guide surface. The guide surface 106 includes a
primary surface portion 106a formed on the primary portion 105a and
a secondary surface portion 106b formed on the secondary portion
105b.
The primary surface portion 106a of the guide surface 106 is
disposed along the rear edge portion of the corresponding window
opening 100. The portion 106a is in a form of a semi-cylindrical
surface and continuous with a rear side portion of an inner
peripheral surface of the corresponding window opening 100. As a
consequence, the primary surface portion 106a is inclined such that
it projects forwardly in the rotating direction R as it goes
radially outwardly of the housing 10 from the center. The secondary
surface portion 106b of the guide surface 106 is flat and inclined
such that it projects in the rotating direction R as it goes
radially outwardly of the housing 10. Owing to a provision of the
fins 106, much more lubricating oil can be supplied into the
housing 10 through the window openings 100 in the same manner as
the first embodiment.
Similar fins 115 as the fins 105 are also formed on the closure 13.
Owing to a provision of the fins 115, much more lubrication oil can
be supplied into the housing 10 through the window openings
110.
FIGS. 14 and 15 show a parallel-axis differential for vehicles
according to a third embodiment of the present invention. Three
window openings 200 are circumferentially equally spacedly formed
in a sleeve portion 11 of a housing. The window openings 200 are
similar in configuration to the window openings 70 of the first
embodiment and formed in the same positions as the window openings
70. A plate member 210 separately situated from the housing 10 and
formed by bending a metal plate is mounted on each window opening
200.
As most clearly shown in FIG. 15, the plate member 210 has a
fitting portion 211. This fitting portion 211 includes a flat
portion 211a to be abutted with a flat surface of the rear side
(rear side when viewed in the rotating direction R of the housing
10 when the vehicle is traveling forwardly) of an inner peripheral
surface of the window opening 200, and a pair of semi-cylindrical
portions 211b to be abutted with inner peripheral surfaces of
opposite end portions (opposite end portions in a direction of a
rotational axis of the housing 10) of the window opening 200.
Furthermore, the plate member 210 includes a fin 212 formed on a
radially external edge of the fitting portion 211, a mounting
portion 213 formed on the center of a radially internal edge of the
fitting portion 211, and a pair of mounting portions 214, 215
connected respectively to the pair of semi-cylindrical portions
211b and projecting radially outwardly and radially inwardly,
respectively.
As shown in FIG. 14, for attaching the plate member 210 to the
corresponding window opening 200, the fitting portion 211 of the
plate member 210 is inserted into the window opening 200 and the
mounting portions 213, 214, 215 are bent so as to be engaged with a
peripheral edge of the window opening 200. In this attaching state,
the fin 212 projects radially outwardly of the housing 10 from a
rear edge portion of the rotating direction R of the window opening
200. The fin 212 is inclined such that it projects forwardly in the
rotating direction R as it goes radially outwardly. A surface of
the fin 212 facing the rotating direction R is served as a guide
surface 216.
* * * * *